1. Programmable End System Services Using SIP
Xiaotao Wu, Henning Schulzrinne
2nd New York Metro Area
Networking Workshop
September 3rd, 2002

2. Today’s Endpoints Processing ability Graphical rendering
Storage capacity
Converged information
Varied platforms
Phones
PCs
PDAs

3. SIP promotes end system services
Two SIP UAs can talk to each other directly.
Service-related information is explicitly contained in SIP headers.
The simplicity of SIP makes it easier for end system to perform services.

4. SIP endpoints are more than IP-based POTS phones

5. SIP service interfaces
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL 1.0//EN" "cpl.dtd">
<cpl>
<incoming>
<address-switch field="origin" subfield="user">
<address is="anonymous">
<reject status="reject"
reason="I don't accept anonymous calls" />
</address>
</address-switch>
</incoming>
</cpl>
@ECHO OFF
IF GOTO BLOCK
GOTO EXIT
:BLOCK
echo SIP/ Busy
:EXIT
CPL
SIP CGI
SIP Servlet
public boolean doInvite(SipRequest req) {
SipResponse res = req.createResponse();
res.setStatus(486);
res.send();
return true; }

7. #! /usr/bin/env perl -w
# Reject messages whose 'From:' matches by
# responding with 486 Busy, redirect the others to voic
print "SIP/ Wait\n\n";
if (defined $ENV{SIP_FROM} && $ENV{SIP_FROM} =~ {
print "SIP/ Don't disturb, I am working\n\n";
} else {
print "SIP/ Redirect\n";
print "Contact: }

8. Describe end system services
Users pay for a bad service because they do not understand why it is not good
Techniques for network services are not good for end system services.

9. Network Services v.s. End System Services

10. Network Services v.s. End System Services
End System Service Language
Network services
End system services
Developer
Experienced developers
Non-programmers
Media and other end system applications
Indirect control
Direct control
User interaction
Indirect
Direct

11. End system service languages
Simple and easy to understand by non-programmers
Platform neutral
Express user interactions
Control media and other end system applications
Extensible to accommodate new services
Restricted to certain class of services, not necessarily Turing-complete

12. Endpoint Service Markup Language (ESML)
XML based language
Platform and underlying programming language neutral
Readable by non-programmers
Defined as an XML schema
Derivation of new types
Pre-defined types
Tree-like structure
Use packages to group events and actions

13. ESML example <esml name="online_call"
require="generic presence ui">
<notification status="online"
priority="0.5">
<address-switch field="origin">
<address
<call />
<alert sound=“foo.au"
text="Calling />
</address>
</address-switch>
</notifying>
</esml>

14. ESML packages SIP user agent SIP im email web Device agent x10 vcr
Presence
agent
presence
Basic user agent
Generic
Media UI
calendar
conference

15. Extend ‘general’ to ‘sip’
<xs:schema targetNamespace="esml:sip"
xmlns:sip="esml:sip"
xmlns:generic="esml:generic"
<xs:complexType name="IncomingType">
<xs:complexContent>
<xs:extension
base="generic:IncomingType">
<xs:attribute name="priority"
type="PriorityType"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>

16. ESML Service Creation

17. Compare to other languages
CPL
SCML
CCXML
CPML, TML, CallXML

18. Conclusion and future work
Service partition between end system services and network services
Feature interaction

19. Thank you!
The End.